Control apparatus for a web positioning system

ABSTRACT

An electro-pneumatic-hydraulic servo control apparatus for laterally moving a web engaging unit in a web positioning system, the servo control apparatus having an electrical web position sensing device for producing an electrical output signal correlative with the lateral deviation of the web from a desired path of web travel; an electro-pneumatic transducer including a pneumatic modulator valve having an electrical valve actuator responsive to the electrical output signal from the web position sensing apparatus for modulating a pneumatic pressure signal applied to a pneumatic operator and an hydraulic positioning means including an hydraulic positioning motor and an hydraulic servo valve operatively connected to the pneumatic operator for reversibly supplying fluid to the hydraulic positioning motor to move the web engaging unit in a direction and at a rate correlative with the deviation of the web from the desired path of web travel. Additional pneumatic-type position sensing devices, including a pneumatic web position sensing device and a unit position sensing device having a pneumatic signal control valve responsive to the position of the web engaging unit, are arranged for selective operation in the control system to control the pressure applied to the pneumatic operator, whereby the web engaging unit can be selectively positioned under the control of different electrical and pneumatic position sensing devices.

United States Patent [191 Ott, Jr.

[ 1 Oct. 23, 1973 CONTROL APPARATUS FOR A WEB POSITIONING SYSTEM [75 Inventor: Robert W. Ott,Jr., Rockford, 111.

[73] Assignee: Rockford Servo Corporation, Rockford, Ill. j

22 Filed: Sept. 20, 1971 [21] Appl. No.: 181,700

[52] US. Cl. 242/57.1

[51] Int. Cl B65h 25/26 [58] Field of Search 242/571; 226/18, 226/19, 20, 21, 22, 23, 45 l [56] References Cited UNITED STATES PATENTS 2,728,533 12/1955 Brunner 242/57.1

3,098,595 7/1963 Shelton 226/45 X 3,284,015 11/1966 King 226/20 X 3,310,942 3/1967 Stanford 242/57.1 X

3,341,099 9/1967 Jacobsen 242/57.1 X

Primary ExamineF-George F. Mautz Assistant ExaminerJohn M. Jillions Attorney-Vernon J. Pillote tus for laterally moving a web engaging unit in a web positioning system, the servo control apparatus having an electrical web position sensing device for producing an electrical output signal correlative with the lateral deviation of the web from a desired path of web travel; an electro-pneumatic transducer including a pneumatic modulator valve having an electrical valve actuator responsive to the electrical output signal from the web position sensing apparatus for modulating a pneumatic pressure signal applied to a pneumatic operator and an hydraulic positioning means including an hydraulic positioning motor and an hydraulic servo valve operatively connected to the pneumatic operator for reversibly supplying fluid to the hydraulic positioning motor to move the web engaging unit in a direction and at a rate correlative with the deviation of the web from the desired path of web travel. Additional pneumatic-type position sensing devices, including a pneumatic web position sensing device and a unit position sensing device having a pneumatic signal control valve responsive to the position of the web engaging unit, are arranged for selective operation in the control-system to control the pressureapplied to the pneumatic operator, whereby the web engaging unit can be selectively positioned under the control of different electrical and pneumatic position sensing devIces.

9 Claims, 11 Drawing Figures United States Patent l 1 [111 3,767,131 Ott, Jr. i 1 Oct. 23, 1973 PATENIEDIIBI 23 973 3.761131 SHEEI 30F 3 CONTROL APPARATUS FOR A WEB POSITIONING SYSTEM BACKGROUND OF THE INVENTION I Web positioning systems utilizing electrical web position sensing devices have heretofore been made and web positioning systems utilizing pneumatic type web position sensing devices have also been made. However, the prior web positioning systems utilizing electrical web position sensing devices could not be used with pneumatic position sensing devices and vice versa.

In web positioning systems it is sometimes desirable to effect movement of the web engaging unit under the control of different web position sensing devices. Thus, while photoelectric web position detectors are advantageously used for sensing a line or printed matter on a travelling web, a pneumatic type web position detector can be advantageously used for sensing the position of different web characteristics such as the web edge. l-Ieretofore, entirely different web position control systems were required for electrical web position detectors and pneumatic web position detectors so that it was not practical to utilize both electrical and pneumatic web position detectors in the same web positioning system. Further, it is also sometimes desirable in web positioning sysems to effect automatic centering or locating of the web engaging unit at a preselected position, when the web engaging unit isnot being moved under the control of a web position sensing device. In general, prior web positioning systems which utilized electrical web position sensing devices required relatively'complex controls for effecting-centering of the web engaging unit.

SUMMARY OF THE INVENTION The present invention relates to a web positioning system wherein a web engaging unit is shiftable laterally relative to the path of web travel and includes an electro-pneumatic-hydraulic servo control apparatus having an electrical web position sensing device for producing an electrical signal correlative with the lateral deviation of the web from a desired path of web travel, an electro-pneumatic transducer including a pneumatic modulator valve having an electroresponsive valve operator for modulating a pneumaticpressure signal correlative with the electrical signal output from the web position sensing device, a pneu.-.

matic operator responsive to the modulated pneumatic pressure signal, and an hudraulic positioning means including an hydraulic motor for moving the web'engaging unit and an hydraulic servo-valve operatively con nected to the pneumatic operator for reversibly supplying hydraulic fluid to the positioning motor. With this arrangement, the power for operating the hydraulic servo valve is supplied by the pneumatic operator and only a very low power is required from the electrical web positioning device for operating the electropneumatic transducer. Moreover, this arrangement facilitates operation of the web engaging unit under the control of different position sensing devices. Thus, a penumatic web position sensing device can be selectively utilized in the control system to modulate the pressure applied to the pneumatic operator and control movement of the web engaging unit in accordance with the web position sensed by the pneumatic sensing device. Further, a unit position sensing device having a pneumatic control valve responsive to the position of the web engaging unit, can be selectively utilized in the control system to effect positioning of the web engaging unit at a selected position relative to the path of web travel, when the web engaging unit is not being shifted under the control of a web position sesing device.

These and other features'of the invention will become better understood from the following description, when taken in connection with the accompanying drawings wherein:

FIG. 1 is a schematic illustration ofa web positioning system utilizing the electro-pneumatic-hydraulic servo control apparatus of the present invention;

FIG. 2 is a diagrammatic side view of the web positioning system of FIG. 1 and illustrating application of the control system thereto;

FIG. 3 is a circuit diagram of the electrical controls for the electro-pneumatic-hydraulic control system of FIG. 1;

FIG. 4 'is a diagrammatic view of an electrical web position detector device, and FIG. 4A is a graph depicting the variation in electrical output signal from the electrical web position detector device with changes in web position;

FIG. 5 is a diagrammatic view of an electropneumatic transducer, and FIG. 5A is a graph depicting the changes in the pneumatic pressure signal produced by the transducer in response to the applied electrical signal from the electrical web position detector device;

FIG. 6 is a diagrammatic view of a pneumatic web position detector device, and FIG. 6A is a graph depicting the variation in the pneumatic pressure signal with web position; and

FIG. 7 is a diagrammatic view of a pneumatic control valve for sensing the lateral position of a web engaging unit, and FIG. 7A is a graph depicting the variation in the pneumatic signal produced by the pneumatic control valve of FIG. 7.

The control apparatus of the present invention is generally adapted for use in web positioning systems to effect relative lateral movement between a travelling web and an apparatus that operates on the web, and the control apparatus may, for example, be utilized to operate a web guide apparatus to laterally shift the travelling web and maintain the same in a preselected relation relative to an apparatus that operates on the web or, alternatively, it may be utilized to shift the apparatus that operates on the web laterally in a manner to follow lateral movement of the travelling web. As utilized herein, the term web engaging unit" refers to a unit that engages the web and is shiftable laterally relative to the path of travel to either laterally shift the web relative to the apparatus that operates on the web or to shift the apparatus that operates on the web in a manner to laterally follow the travelling web. In the embodiment illustrated in FIG. 2, the web engaging unit comprises a web unwind unit 10 which is shiftable in a direction laterally relative to the path of web travel to maintain the web in a preselected lateral position relative to an apparatus 11 which performs an operation on the web. As diagrammatically shown in FIG. 2, a roll 12 of web material is supported by a shaft 13 on a shiftable unwind carriage 14 which is mounted as by followers 15 slidable on rods 16 for shifting movement in a direction laterally of the path of travel of the web. The web W, as it unwinds from the roll 12, passes over one or more idler rolls l7, 18 which are mounted on the unwind carriage 14 for rotation about their respective axis 17a, 18a. The idler rolls 17 and 18 are thus shiftable laterally with the unwind carriage and the web, after leaving the last idler roll 18 on the unwind carriage passes over one or more idler rolls 21, 22, herein shown supported for axial rotation about their axis 21a, 22a, respectively on a stationary frame structure 23. In the embodiment illustrated, the apparatus 11 for performing an operation on the web comprises a slitter mechanism mounted on the stationary frame structure 23 and which operates to slit the longitudinally travelling web as it passes from idler roll 21. The web,- after being slit by the slitter mechanism, passes to rewind rolls 25 and 26 which are driven in a manner well known in the art to rewind the separated web sections.

The control apparatus in the present invention utilizes an electric type web position sensing device 31 such as a photoelectric type web position sensor for producing an electrical output signal correlative with the deviation of the web from the desired path of web travel; an electro-pneumatic transducer 32 responsive to the output signal of the electric web position detector and operative to modulate a pneumatic signal correlative with the electrical signalproduced by the electrical web position detector, a pneumatic operator 33 which is responsive to the modulated pneumatic signal and which operates an hydraulic servo-valve 34 to reversibly supply fluid to an hydraulic positioning motor 35 at a rate and in a direction correlative with the movement of the pneumatic operator. The electropneumatic-hydraulic control system is arranged so that other pneumatic position detecting apparatus can be selectively used in the control system to control positioning of the web engaging unit 10. Thus, a pneumatic type web position detecting device 36 is provided and is selectively operable to modulate the pressure signal applied to the pneumatic operator 33 for moving the servo valve 34 under the control of the pneumatic web position detector. In addition, a unit position control device 37 comprising a pneumatic control valve is provided for sensing the position of the web engaging unit and is selectively operable to modulate the pressure applied to the pneumatic operator 33, so as to enable the positioning of the unit 10 under the control of the unit position detector 37. Manual positioning controls are also advantageously provided for controlling the pressure applied to the pneumatic operator 33 for the hydraulic servo-valve 34 to enable manual control of the position of the web engaging unit 10.

The photoelectric web position sensing device 31 can be of conventional construction and may, for example, be of the reflective type wherein the light transmitter and the photoelectric receiver are disposed on the same side of the web, with the photo-electric receiver actuated in response to the light reflected from the travelling web to sense a line or printed matter on the web. Alternatively, in applications where the photoelectric sensor is intended for use in sensing the web edge or for sensing web areas of relatively different density in a partially transparent or translucent web, the photoelectric position sensing device 31 can be of the type wherein the light transmitter is located on one side of the web and the receiver at the other side of the web so that the receiver is operated by variations in the light transmitted past or through the web. In the embodiment illustrated, the photoelectric web position detector 31 is of the reflective type having an eye 31a and, as shown in FIG. 2, is mounted as by bracket 41 on a cross rod 42 secured to the stationary support structure 23. In the embodiment illustrated, the photoelectric web position detector 31 is arranged to sense printed matter on the travelling web such as a line indicated at L in FIG. 2. The photoelectric web position sensing device includes an amplifier 31!; and is arranged to produce an electrical output signal from the amplifier designated E in F168. 4 and 4A having voltage-current characteristics that vary in amplitude correlative with the deviation of the web characteristic being sensed relative to the desired path of web travel.

The output of the electrical web position detecting device is applied through conductors 46 to an electroresponsive actuator 47 for the electro-pneumatic transducer 32. The electro-pneumatic transducer can be of a known type such as a moving coil type or a flapper valve type. As diagrammatically shown in FIG. 5, the actuator 47 includes a coil 48 on a pole piece 49 of ferromagnetic material which is operable to move an armature 51 of ferromagnetic material in response to the electric signal E applied to the coil. The electropneumatic transducer 32 also includes a pneumatic control valve having a pneumatic orifice 52 mounted on a support structure 53 and a movable valve element 54 which is mounted for movement relative to the pneumatic orifice 52 by valve support member 55. The armature 51 is connected to the valve member to move the valve member relative to the orifice 52, and a means such as a spring 57 is provided to urge the valve to its closed position. The force supplied by the spring 57 is preferably adjustable as by a screw 58 to facilitate calibration of the valve movement with the applied voltage E.

The orifice 52 is connected through a line 59 to the pneumatic operator 33 for the hydraulic servo-valve 34 and, preferably, the electro-pneumatic transducer is located close to the pneumatic operator 33 to minimize the length of the line 59 and hence the volume of air in the line between the transducer and the pneumatic operator so that the pneumatic operator will rapidly respond to changes in the pneumatic signal produced by the transducer. The pneumatic operator 33 and hyrdaulic servo-valve 34 form a part of a pneumatichydraulic servo control apparatus, of the type which is also adapted for use with pneumatic type position sensing devices. While various pneumatic-hydraulic servo control apparatus are available, the pneumatichydraulic servo control apparatus illustrated herein is of the type disclosed in US. Pat. No. 3,407,706 issued Oct. 29, 1968 to Robert W. Ott, Jr. As diagrammatically shown in FIG. 1, the pneumatic-hydraulic servo control apparatus includes a fluid reservoir 61 containing hydraulic fluid 62, an hydraulic servo-valve casing 63, and a movable flow reversing valve member 64. The casing has a pressure inlet port 630, first and second controlled outlet ports 63b, 63c, and return ports 63d and 63e. The valve element 64 is hydraulically balanced and has spaced spools 64a and 64b which are operative in a null position shown in FIG. 1, to block flow from the inlet port 63a to the controlled outlet ports 63b and 63c, and which are operative when moved in either direction from the null position, to reversibly supply the fluid from the inlet port to one or the other of the controlled outlet ports at a rate proportional to the movement of the valve element from its neutral or null position. The pressure responsive operator includes a diaphragm 67 which is connected to the valve element 64 and whichhas a housing 68 defining a pressure chamber 68a at least at one side of the diaphragm. In the present device, casing 68 is clamped to a top wall 69 for the reservoir and defines a second chamber 68b at the other side of the diaphragm, which second chamber is herein shown vented into the atmosphere through a vent 71. The diaphragm 67 is peripherally sealed to the casing 68 and top wall 69 by seal rings 72. Pneumatic pressure is supplied to the chamber 68a from a source, herein shown in the form of a multistage centrifugal air pump 75 having rotary centrifugal propellers 75a and stationary diffuser stages 75b which are operative to draw air from the atmosphere through a filter 76 at the centrifugal air pump inlet and to discharge air at elevated pressure through a discharge line 77. The centrifugal air pump is driven at a substantially constant speed by a motor 78 through a belt drive 80 and, when driven at the constant speed, the centrifugal air pump will maintain a substantially constant pressure in the pneumatic discharge line 77. If desired, the pressure can be supplied from a source such as a plant air supply through a regulator capable of accurately maintaining a low substantially constant discharge pressure. Delivery line 77 is connected through a pneumatic flow restrictor 79 and line 81 to the pressure chamber 68a for the pneumatic operator and the pressure chambers otherwise connected through a line 82 to the conduit 59 leading to the pneumatic modulator 32. Hydraulic fluid pressure is supplied by hydraulic pump 85, conveniently driven by the motor 78 used for driving the air generator, and which hydraulic pump has an inlet line 86 connected to the reservoir 61 and a discharge line 87 connected to the inlet passage 63a of the hydraulic servo-valve. A conventional filter 89 and relief valve 91 is provided in the discharge line 87 to respectively filter the fluid delivered to the servo-valve and to limit th maximum fluid pressure. Controlled outlet ports 63b and 630 of the hydraulic servo-valve are connected through lines 92a and 92b to the hydraulic positioning motor 35 to reversibly operate the same. I

The pressure in the chamber 68a builds up substantially to the maximum pressure supplied to the pneumatic delivery line 77, for example 6 to 8 inches of water column, when flow from the pressure chamber 68a is completely shut off and, when the modulator valve is opened to allow flow from the chamber, the pneumatic flow restrictor 79 produces a pressure drop proportional to the flow so as to reduce the pressure in the chamber 68a. In the embodiment shown, pressure in the pressure chamber 68a normally urges the hydraulic servo-valve to a raised position and a spring 98 is provided to yieldably oppose upward movement of the valve member, the spring force being adjustable as by screw 99. In general, the screw is adjusted so that the force supplied by spring 98 moves the valve to its neutral or null position shwon in FIG. 1, when the pressure in chamber 68a is at a value intermediate maximum pneumatic pressure supplied by the pressure generator 75, and the minimum value which occurs when the modulator valve is fully opened. The spring 57 of the modulator is, in turn, adjusted by the screw 58 to control opening movement of the modulator valve member in response to the electrical signal E applied to the coil 48. The graph in FIG. 4A is an idealized curve which depicts variations in the output electrical signal E from the photoelectric web position sensing device in response to lateral variation in the position of the web characteristic being sensed. The photoelectric web sensing apparatus 31 is arranged to sense lateral movement of the web characteristics such as line L as it moves laterally between positions designated di and d2 and the output electrical signal E correspondingly varies between limits designated E1 and E2. When the web characteristic such as a line L is at an intermediate position designated dm, the output electrical signal reaches a value Em intermediate the values E1 and E2 and the spring 57 of the modulator is preferably adjusted so that, when the signal of the value Em is applied to the electro-pneumatic transducer, it opens the orifice 52 to reduce the pressure on the pressure responsive operator to an intermediate value such as the value designated Pm in the graph in FIG. 5A. The screw 99 for the spring 98 in the pressure responsive operator is preferably adjusted so as to move the hydraulic servo-valve 34 to its neutral or null position shown in FIG. 1, when the pressure in the chamber 68a reaches the intermediate value Pm. As the electrical output signal E varies from the value Em, it respectively increases and decreases the opening of the modulator valve to respectively decrease and increase the pressure on the pneumatic operator. This in turn moves the servo-valve in a direction and through a distance proportional to the electrical signal E to reversibly operate the hydraulic positioning motor 35 at a rate and in a direction proportional to the deviation of the web from the desired path of web travel.

The control system is also adapted for use with pneumatic type web position detecting device 36. As shown in FIG. 2, the pneumatic web position detector device 36 is mounted as by a bracket 101 on a rod 102 attached to the support structure 23 in a position to sense the lateral deviation of the edge of the web W. The pneumatic web position sensing device 36 is conveniently of the type disclosed in the aforementioned U.S. Pat. No. 3,407,706 and, as best shown in FIG. 6, includes a transmitting orifice 104i disposed on one side of the web and a sensing orifice 105 located at the other side of the web. The transmitting orifice 104 is connected through a conduit 106 to communicate with the pneumatic delivery line 77 ahead of the flow restrictor 79 to transmit an air stream from orifice 104 across the web edge. The sensing orifice 105 is connected through a line 107 to a fitting 108 that communicates through conduit 82 with the pressure chamber 68a. The web edge as it moves laterally between the transmitting and receiving orifices 10 i and 105, variably interrupts the transmitting orifice to variably modulate the pressure at the receiving orifice and this pressure is sensed through lines 107 and 82 by the pressure responsive diaphragm 67. In order to enable selective positioning of the web engaging unit under the control of either the electrical web position sensing device 31 or the pneumatic web position sensing device 32, control valves 115, 116 and 117 are provided in the lines 59, 107 and 106 respectively. As diagrammatically shown in FIG. 1,,the valves -117 are of the normally closed type and have electro-responsive operators 115a, 116a, and 117a respectively, which are operative, when energized, to move the respective valves to their open position' It is generally desirable to position the web engaging unit in a preselected position, herein sometimes referred to as center position, when the web engaging unit is not under the control of one or the other of the web position sensors, and the unit position sensing device 37 is arranged to control the pneumatic pressure on the diaphragm 67 of the pressure responsive operator in accordance with the position of the web engaging unit relative to a preselected or centered position. As diagrammatically illustrated in FIG. 7, the unit position sensing device 37 comprises a control valve having a body 121 with an orifice 122 connected through a line 123 and a control valve 124 to a fitting 126 that communicates with the line 82 leading to the pressure responsive chamber 68a. A valve member, herein shown in the form of a lever 129 is pivotally mounted on the valve body and is movable across the orifice 122 to variably interrupt flow through the orifice. The valve member 129 is yieldably urged in one direction as by a spring 131 and has a follower 132 arranged to engage the movable carriage 14 of the web engaging unit 11 to be moved thereby. A stop 133 limits movement of the valve member by the spring to a position closing orifice 122. As shown in the graph of FIG. 7A, the valve member 129 is operative in a mid-position thereof designated Uc to regulate flow through the orifice 122 to a valve such that the pressure drops to a value such as the intermediate value Pm previously described and, as the web engaging unit moves in one direction or the other from this mid-position, it either increases or decreases the rate of flow through the orifice to correspondingly decrease or increase the pressure on the pressure responsiveoperator 67. Control valve 124 is also of the normally closed type, as diagrammatically shown in FIG. 1, and has an electro-responsive operator 1240 which is operative, when energized to move the valve 124 to its open position.

It is also sometimes desirable to manually control the positioning motor 35 to effect manual control of the position of the web engaging unit. For this purpose, a normally closed bleeder valve 138 is connected through a line 139 to a fitting 141 and also communicates through conduit 82 with the chamber 68a. Valve 138 has an electro-responsive operator 138a which is operative, when energized, to move the bleeder valve 138 to an open position to thereby reduce pressure on the pressure responsive operator 67. A hydraulic control valve 145 is provided in the lines 92a, 92b leading to the hydraulic positioning motor 35. The valve 145 is operative in one position to block flow to and from the hydraulic positioning motor to hold the unit in a fixed position, and it is operative in the other position to pass fluid to and from the positioning motor 35.

An electrical circuit for the control apparatus is schematically shown in FIG. 3. The circuit includes a motor control relay 151 connected in series with a normally closed stop switch 152 and a normally open start switch 153. The start switch 153, when closed, energizes the relay 151 to close relay contacts 151a, l51b and 1510.

. Contacts 151a, when closed, establish a holding circuit in parallel with the start switch 153 so as to maintain the relay 151 energized under the control of the stop switch 152, and contacts 151b and 151C establish a circuit to the motor 78 to energize the same. A secondary circuit energized from transformer 154 includes a multiple position switch having switch sections 156 and 157 which are movable in unison through positions designated E, A, C and M. In the E position as shown, switch 156 establishes a circuit to the electro responsive actuator 115a for the valve 115 to connect the electro pneumatic transducer 32 with the pressure responsive operator 33. The other pneumatic control valves 138, 116 and 117 remain closed when the switch 156 is in the E position and switch 157 in the E position establishes a circuit to the solenoid 145a of the hydraulic control valve 145 to open the valve and allow flow to flow to and from the hydraulic positioning motor 35 under the control of the hydraulic servo-valve 34. Thus, when the switches 156 and 157 are in the E position, positioning of the web engaging unit 11 is under the control of the electrical web positioning apparatus. When switches 156 and 157 are moved to the A position, electro-responsive operator a is deenergized and electro-responsive operators 116a, and 117a, are energized to open the lines 107 and 106 leading to the pneumatic web positioning detecting device 36. In the A position, switch 157 establishes a circuit to the actuator a of the hydraulic control valve 145 to open the latter so that the position of the web engaging unit can be controlled by the pneumatic web position detector. When the switch 156 is moved to the C position, the solenoid 124a is energized to open valve 124 while the other pneumatic control valves are deenergized and closed. Switch 157 maintains a circuit to the solenoid 145a of the hydraulic control valve 145 so that the position of the web engaging unit 11 can be controlled by the unit position sensing device 37. When the switch 156 is moved to its M position, it establishes a circuit through normally open switch 161a to the actuator 138a for the bleed valve 138. Switch 157, when in its M position, does not establish any circuit to the operator 145a for the hydraulic control valve 145. Instead, the circuit to the operator 145a is under the control of normally open switches 161b and 163. Switch 1611) is operatively connected to switch 161a so that, when switch 161a is closed to energize the actuator 138a to open the bleed valve, switch 161b is also closed to energize the operator 145a for the hydraulic valve to open the latter. Thus, when switches 161a and l61b are closed, they simultaneously reduce the pressure on the pressure responsive operator and open the hydraulic circuit to the positioning motor so that the pneumatic operator 33 moves the control to a position supplying hydraulic fluid to line 92b to cause the positioning motor 35 to move the unit 11 in one direction. When switch 163 is closed, it opens the circuit to the hydraulic positioning motor but, since the bleed valve 138 remains closed, the pressure on the pneumatic operator 33 moves the hydraulic control valve to a position supplying hydraulic fluid to line 92a to move the web engaging unit in the opposite direction. It is also diagrammatically shown in FIG. 3, the amplifier 31b and electrical web position sensing apparatus 31 are energized under the control of a switch 171 and transformer 172.

From the foregoing, it is thought that the construction and operation of electro-pneumatic-hydraulic control system will be readily understood. The position of the web engaging unit 11 can be selectively changed by the hydraulic web positioning motor 35 under the control of either the electrical web position sensor 31; the pneumatic web position sensor 36; the unit position sensing device 37 or under the control of manual switches 161a, [61b and 163. the phasing of the electrical and pneumatic signals produced by the different position sensing devices must, of course, be correlated so that each produces a similar change in the pneumatic signal applied to the operator for a corresponding directional change in the position of the device. Thus, if the electrical web position sensing apparatus produces an output signal E2 that increases as the web position shifts to the right as viewed in FIG. 1, then it will reduce the pressure on the pressure responsive operator and cause the hydraulic control valve 34 to move downwardly. As the valve moves downwardly, it applies pressure to line 92b to move the web engaging unit to the left, that is in a direction to correct deviation of the web from the desired path of web travel. If the pneumatic web positioning device 36 is also arranged as shown in FIG. 1 to sense the position of the right edge of the web, movement of the web to the right will also decrease the pressure on the pressure responsive operator and also cause the servo-valve to supply fluid to the positioning motor 35 to move the web engaging unit to the left. As diagrammatically shown in FIG. 1, the unit position sensing device is also mounted at the right side of the unit and is arranged so that the valve member 129 progressively uncovers the port 122 as the unit moves to the right. this causes a reduction of pressure on the pressure responsive operator which, as previously described, causes a shifting movement of the unit 10 toward the left, and movement of the unit 10 stops when the valve member 129 reaches its centered position shown in FIG. 7. Manual controls 161a, when closed, open the bleed valve 138 to reduce pressure on the pneumatic operator 33 so as to cause the web engaging unit to shift to the left and, when switch 163 is closed, it causes the unit to move to the right.

The variation in electrical and pneumatic signals are shown in the graphs of FIGS. 4A-6A as having a linear or straight-line relationship. It is to be understood however, that these are merely illustrative of the relationships involved and that, in practice, the relationships depicted in the graphs would not necessarily be linear and could be non-linear or curved.

While a preferred embodiment of the electropneumatic-hydraulic control system has been herein disclosed, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a web positioning system having a web engaging unit shiftable laterally relative tothe path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising:

an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative in amplitude with the lateral deviation of the web from a desired path of web travel; I

pneumatic operator means including a pressure responsive movable wall means'and pneumatic pressure generator means for applying fluid pressure to said movable wall means;

pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to change the amplitude of the pneumatic pressure applied to said movable wall means between upper and lower limits correlative with the position of said modulator valve element in said modulator valve means, and electroresponsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for variably positioning said modulator valve element in accordance with the amplitude of the electrical output signal from said web position sensing device;

hydraulic positioning means including a reversible hydraulic motor for moving said web engaging unit, means including hydraulic fluid pressure supply means and an hydraulic servo-valve having a servovalve member movable from a null position to reversibly supply hydraulic fluid to said hydraulic motor at a rate correlative with the movement of the hydraulic servo-valve member from said null position, and means connecting said servo-valve member to said movable wall means for movement thereby from said null position, when the pneumatic pressure on said wall means is at a selected value intermediate said upper and lower limits, in a direction and amplitude correlative with the change in amplitude of the pneumatic pressure on said wall means from said selected value.

2. The combination of claim 1 wherein said electrical web position sensing device comprises a photoelectric web position sensing device.

3. The combination of claim 1 including a pneumatic web position sensing device having orifice means positioned to sense lateral deviation ofa web from a desired path of web travel, and conduit means operatively connecting said orifice means to said pneumatic operator means for varying the pneumatic pressure on said movable wall means between substantially the same upper and lower limits correlative with the lateral deviation of the web from a desired path of web travel;

and selector means selectively operable to render either said electrical position sensing device or said pneumatic position sensing device inoperative to vary the pressure on said movable wall means of said pneumatic operator means.

4. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising:

an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative with the lateral deviation of the web from a desired path of web travel;

pneumatic operator means including a pressure responsive movable wall means and pneumatic pressure generator means for applying fluid pressure to said movable wall means;

pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to vary the pneumatic pressure applied to said movable wall means correlative with the position of said modulator valve element in said modulator valve means, and electroresponsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for'moving said modulator valve element in accordance with the electrical output signal from said web position sensing device; hydraulic positioning means including an hydraulic motor for moving said web engaging unit, and means including hydraulic fluid pressure supply means and an hydraulic servo-valve operatively connected to said pneumatic operator means for reversibly supplying hydraulic fluid to said hydraulic motor at a rate correlative with the movement position relative to the path of web travel, said unit position sensing device comprising a unit position control valve means having conduit means connecting the same to said pneumatic operator means of the hydraulic servo-valve; and a position control valve element movable to unit position sensing device for sensing displacevary the pneumatic pressure applied to said movment of said web engaging unit from a preselected able wall means, and means responsive to the posiposition relative to the desired path of web travel, tion of said web engaging unit for moving said posisaid unit position sensing device comprising a unit tion control valve element to vary the pressure on position control valve means having conduit means said movable wall means in accordance with the connecting the same to said pneumatic operator displacement of said web engaging unit from said means and a movable position control valve elepreselected position;

ment movable to vary the pneumatic pressure apand selector means for selectively controlling which plied to said movable wall means, and means reof said several position sensing devices is operable sponsive to the position of said web engaging unit 15 to vary the pressure on said movable wall means for moving said position control valve element to vary the pressure on said movable wall means of said pneumatic operator means in accordance with the displacement of said web engaging unit from and for rendering the others of said sensing devices inoperative to vary the pressure on said movable wall means.

6. in a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising:

an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative in amplitude with the lateral deviation of the web from a desired path of web travel; pneumatic operator means including a pressure responsive movable wall means and pneumatic pressaid preselected position; and selector means selectively operable to render either said electrical position sensing device or said unit position sensing device inoperative to vary the pressure on said movable wall means. 5. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising;

an electrical web position sensing device for sensing web from a desired path of web travel; unit position sensing device for sensing displacement of said web engaging unit from a preselected the lateral position of a travelling web and having sure generator means for applying fluid pressure to means for producing an electrical output signal said movable wall means; correlative with the lateral deviation of the web pneumatic modulator valve means having conduit from a desired path of web travel; means connecting the same to said pneumatic oppneumatic operator means including a pressure reerator means and a movable modulator valve elesponsive movable wall means and pneumatic presment operable to change the amplitude of the sure generator means for applying fluid pressure to pneumatic pressure applied to said movable wall said movable wall means; means between upper and lower limits correlative pneumatic modulator valve means having conduit with the position of said modulator valve element means connecting the same to said pneumatic opin said modulator valve means, and electroerator means and a movable modulator valve eleresponsive valve operator means responsive to said ment operable to vary the pneumatic pressure apelectrical output signal from said electrical web poplied to said movable wall means correlative with sition sensing device for variably positioning said the position of said modulator valve element in said modulator valve element in accordance with the modulator valve means, and electro-responsive amplitude of the electrical output signal from said valve operator means responsive to said electrical web position sensing device; output signal from said electrical web position hydraulic positioning means including a reversible sensing device for moving said modulator valve elehydraulic motor for moving said web engaging unit, ment in accordance with the electrical output sigmeans including hydraulic fluid pressure supply nal from said web position sensing device; means and an hydraulic servo-valve having a servohydraulic positioning means including an hydraulic valve member movable from a null position to remotor for moving said web engaging unit, and versibly supply hydraulic fluid to said hydraulic means including hydraulic fluid pressure supply motor at a rate correlative with the movement of means and an hydraulic servo-valve operatively the hydraulic servo-valve member from said null connected to said pneumatic operator means for position, and means connecting said servo-valve reversibly supplying hydraulic fluid to said hydraumember to said movable wall means for movement lic motor at a rate correlative with the movement thereby from said null position, when the pneumaof the hydraulic servo-valve; tic pressure on said movable wall means is at a sea pneumatic web position sensing device having orilected value intermediate said upper and lower limfice means positioned to sense lateral deviations of its, in a direction and magnitude correlative with a web from a desired path of web travel and conthe change in amplitude of the pneumatic pressure duit means operatively connecting said orifice on said movable wall means from said selected means to said pneumatic operator means for varyvalue; ing the pneumatic pressure on said movable wall at least one other position sensing device having orimeans correlative with the lateral deviation of the fice means connected through conduit means to said pneumatic operator means and operable to vary the pressure on said movable wall means substantially between said upper and lower limits;

and selector means for selectively controlling which of said several position sensing devices is operable to vary the pressure on said movable wall means and for rendering the others of said sensing devices inoperative to vary the pressure on said movable wall means.

7. The combination of claim 6 wherein said other position sensing device comprises a pneumatic web edge detector device having said orifice means positioned to be variably interrupted by a travelling web.

8. The combination of claim 6 wherein said selector means includes valves controlling communication between each position sensing device and the pneumatic operator means, and means for selectively operating said last-mentioned valves to establish communication between one positioning means and the pneumatic operator means while blocking communication between another position sensing device and the pneumatic operator means.

9. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising:

an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal I correlative with the lateral deviation of the web from a desired path of web travel;

pneumatic operator means including a pressure responsive movable wall means and pneumatic pressure generator means for applying fluid pressure to said movable -wall means;

pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to vary the pneumatic pressure applied to said movable wall means correlative with the position of said modulator valve element in said modulator valve means, and electro-responsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for moving said modulator valve element in accordance with the electrical output signal from said web position sensing device; hydraulic positioning means including an hydraulic motor for moving said web engaging unit, and means including hydraulic fluid pressure supply means and an hydraulic servo-valve operatively connected to said pneumatic operator means for reversibly supplying hydraulic fluid to said hydraulic motor at a rate correlative with the movement of the hydraulic servo-valve; at least one other position sensing device having orifice means connected through conduit means to said pneumatic operator means and operable to vary the pressure on said movable wall means, said other position sensing device comprising a control valve having a movable control valve element for variably interrupting said orifice means, and means for moving said movable control valve element in response to the position of the web engaging unit; and selector means for selectively controlling which of said several position sensing devices is operable to vary the pressure on said movable wall means and for rendering the others of said sensing devices inoperative to vary the pressure on said movable wall means. 

1. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising: an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative in amplitude with the lateral deviation of the web from a desired path of web travel; pneumatic operator means including a pressure responsive movable wall means and pneumatic pressure generator means for applying fluid pressure to said movable wall means; pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to change the amplitude of the pneumatic pressure applied to said movable wall means between upper and lower limits correlative with the position of said modulator valve element in said modulator valve means, and electro-responsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for variably positioning said modulator valve element in accordance with the amplitude of the electrical output signal from said web position sensing device; hydraulic positioning means including a reversible hydraulic motor for moving said web engaging unit, means including hydraulic fluid pressure supply means and an hydraulic servovalve having a servo-valve member movable from a null position to reversibly supply hydraulic fluid to said hydraulic motor at a rate correlative with the movement of the hydraulic servovalve member from said null position, and means connecting said servo-valve member to said movable wall means for movement thereby from said null position, when the pneumatic pressure on said wall means is at a selected value intermediate said upper and lower limits, in a direction and amplitude correlative with the change in amplitude of the pneumatic pressure on said wall means from said selected value.
 2. The combination of claim 1 wherein said electrical web position sensing device comprises a photoelectric web position sensing device.
 3. The combination of claim 1 including a pneumatic web position sensing device having orifice means positioned to sense lateral deviation of a web from a desired path of web travel, and conduit means operatively connecting said orifice means to said pneumatic operator means for varying the pneumatic pressure on said movable wall means between substantially the same upper and lower limits correlative with the lateral deviation of the web from a desired path of web travel; and selector means selectively operable to render either said electrical position sensing device or said pneumatic position sensing device inoperative to vary the pressuRe on said movable wall means of said pneumatic operator means.
 4. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising: an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative with the lateral deviation of the web from a desired path of web travel; pneumatic operator means including a pressure responsive movable wall means and pneumatic pressure generator means for applying fluid pressure to said movable wall means; pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to vary the pneumatic pressure applied to said movable wall means correlative with the position of said modulator valve element in said modulator valve means, and electro- responsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for moving said modulator valve element in accordance with the electrical output signal from said web position sensing device; hydraulic positioning means including an hydraulic motor for moving said web engaging unit, and means including hydraulic fluid pressure supply means and an hydraulic servo-valve operatively connected to said pneumatic operator means for reversibly supplying hydraulic fluid to said hydraulic motor at a rate correlative with the movement of the hydraulic servo-valve; a unit position sensing device for sensing displacement of said web engaging unit from a preselected position relative to the desired path of web travel, said unit position sensing device comprising a unit position control valve means having conduit means connecting the same to said pneumatic operator means and a movable position control valve element movable to vary the pneumatic pressure applied to said movable wall means, and means responsive to the position of said web engaging unit for moving said position control valve element to vary the pressure on said movable wall means of said pneumatic operator means in accordance with the displacement of said web engaging unit from said preselected position; and selector means selectively operable to render either said electrical position sensing device or said unit position sensing device inoperative to vary the pressure on said movable wall means.
 5. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising; an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative with the lateral deviation of the web from a desired path of web travel; pneumatic operator means including a pressure responsive movable wall means and pneumatic pressure generator means for applying fluid pressure to said movable wall means; pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to vary the pneumatic pressure applied to said movable wall means correlative with the position of said modulator valve element in said modulator valve means, and electro-responsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for moving said modulator valve element in accordance with the electrical output signal from said web position sensing device; hydraulic positioning means including an hydraulic motor for moving said web engaging unit, and means including hydraulic fluid pressure supply means and an hydraulic servo-valve operatively connected to said pneumatic operator means for reversibly supplying hydrauliC fluid to said hydraulic motor at a rate correlative with the movement of the hydraulic servo-valve; a pneumatic web position sensing device having orifice means positioned to sense lateral deviations of a web from a desired path of web travel and conduit means operatively connecting said orifice means to said pneumatic operator means for varying the pneumatic pressure on said movable wall means correlative with the lateral deviation of the web from a desired path of web travel; a unit position sensing device for sensing displacement of said web engaging unit from a preselected position relative to the path of web travel, said unit position sensing device comprising a unit position control valve means having conduit means connecting the same to said pneumatic operator means and a position control valve element movable to vary the pneumatic pressure applied to said movable wall means, and means responsive to the position of said web engaging unit for moving said position control valve element to vary the pressure on said movable wall means in accordance with the displacement of said web engaging unit from said preselected position; and selector means for selectively controlling which of said several position sensing devices is operable to vary the pressure on said movable wall means and for rendering the others of said sensing devices inoperative to vary the pressure on said movable wall means.
 6. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising: an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative in amplitude with the lateral deviation of the web from a desired path of web travel; pneumatic operator means including a pressure responsive movable wall means and pneumatic pressure generator means for applying fluid pressure to said movable wall means; pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to change the amplitude of the pneumatic pressure applied to said movable wall means between upper and lower limits correlative with the position of said modulator valve element in said modulator valve means, and electro-responsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for variably positioning said modulator valve element in accordance with the amplitude of the electrical output signal from said web position sensing device; hydraulic positioning means including a reversible hydraulic motor for moving said web engaging unit, means including hydraulic fluid pressure supply means and an hydraulic servo-valve having a servo-valve member movable from a null position to reversibly supply hydraulic fluid to said hydraulic motor at a rate correlative with the movement of the hydraulic servo-valve member from said null position, and means connecting said servo-valve member to said movable wall means for movement thereby from said null position, when the pneumatic pressure on said movable wall means is at a selected value intermediate said upper and lower limits, in a direction and magnitude correlative with the change in amplitude of the pneumatic pressure on said movable wall means from said selected value; at least one other position sensing device having orifice means connected through conduit means to said pneumatic operator means and operable to vary the pressure on said movable wall means substantially between said upper and lower limits; and selector means for selectively controlling which of said several position sensing devices is operable to vary the pressure on said movable wall means and for rendering the others of said sensing devices inoperative to vary the pressure on said movable wall mEans.
 7. The combination of claim 6 wherein said other position sensing device comprises a pneumatic web edge detector device having said orifice means positioned to be variably interrupted by a travelling web.
 8. The combination of claim 6 wherein said selector means includes valves controlling communication between each position sensing device and the pneumatic operator means, and means for selectively operating said last-mentioned valves to establish communication between one positioning means and the pneumatic operator means while blocking communication between another position sensing device and the pneumatic operator means.
 9. In a web positioning system having a web engaging unit shiftable laterally relative to the path of web travel, an electro-pneumatic-hydraulic servo control apparatus for said web engaging unit, comprising: an electrical web position sensing device for sensing the lateral position of a travelling web and having means for producing an electrical output signal correlative with the lateral deviation of the web from a desired path of web travel; pneumatic operator means including a pressure responsive movable wall means and pneumatic pressure generator means for applying fluid pressure to said movable wall means; pneumatic modulator valve means having conduit means connecting the same to said pneumatic operator means and a movable modulator valve element operable to vary the pneumatic pressure applied to said movable wall means correlative with the position of said modulator valve element in said modulator valve means, and electro-responsive valve operator means responsive to said electrical output signal from said electrical web position sensing device for moving said modulator valve element in accordance with the electrical output signal from said web position sensing device; hydraulic positioning means including an hydraulic motor for moving said web engaging unit, and means including hydraulic fluid pressure supply means and an hydraulic servo-valve operatively connected to said pneumatic operator means for reversibly supplying hydraulic fluid to said hydraulic motor at a rate correlative with the movement of the hydraulic servo-valve; at least one other position sensing device having orifice means connected through conduit means to said pneumatic operator means and operable to vary the pressure on said movable wall means, said other position sensing device comprising a control valve having a movable control valve element for variably interrupting said orifice means, and means for moving said movable control valve element in response to the position of the web engaging unit; and selector means for selectively controlling which of said several position sensing devices is operable to vary the pressure on said movable wall means and for rendering the others of said sensing devices inoperative to vary the pressure on said movable wall means. 